MS 


University  of  California— College  of  Agriculture, 

AGRICULTURAL  EXPERIMENT  STATION. 

E.   W.  HILGAHD,  Director. 


THE  PHYLLOXERA  OF  THE  VINE. 


By  FREDERIC  T.  BIOLETTL 


VITIS  VULPINA  (Riparia), 
Typical  wild  vine  from  North  America, 
(Resistant.) 


VITIS  VINIFERA, 

Wild  vine  from  the  Caucasus. 

(Non-resistant.) 


A.    J.    JOHNSTON, 


BULLETIN  No.   131. 

(Berkeley,  Mav,  1901.)  ;TY  OF  C/ 

LIBRARY 

COLLEGE  OF  AGRICULTURE 

DAVIS 

SACRAMENTO: 

:     :      :     superintendent   state   printing. 
1901. 


AVAILABLE  PUBLICATIONS  ON  VINE   AND  OLIVE  GROWING. 


The  following  'publications  will  be  sent  free  on  application: 

Resistant  Vines:  Appendix  to  Viticultural  Report  for  1896. 

Bui.  116:  The  California  Vine-Hopper. 

Bui.  119:  Vine  Pruning. 

Bui.  120:  The  Olive  Knot. 

Bui.  123:  Olives — Cultivation,  Oil-Making,  Pickling,  Varieties. 

Bui.  127:  Bench-Grafting  Resistant  Vines. 

Bui.  129:  Condition  of  Olive  Culture  in  California. 

Bui.  130:  Preservation  of  Unfermented  Grape-Must. 

Viticultural  Report  for  1887-95.  (Contains  on  page  454  a  list  of  the 
publications  of  the  State  Board  of  Viticulture,  which  will  be  sent 
on  receipt  of  necessary  postage.) 

Agricultural  Report  for  1895-96,  1896-97,  containing: 
California  Olives. 
Wine,  Table,  and  Raisin  Grapes  at  the  substations. 

Agricultural  Report  for  1897-98,  containing: 
Notes  on  the  California  Vine-Hopper. 
Revision  of  Bulletin  119:  Vine  Pruning. 


THE  PHYLLOXERA  OF  THE  VINE. 


The  late  discovery  of  the  phylloxera  of  the  vine  in  several  important 
grape-growing  districts  which  have  hitherto  been  regarded  as  exempt 
has  awakened  widespread  interest,  and  even  alarm,  among  both  wine- 
and  raisin-producers.  In  order  to  satisfy  the  demand  for  information 
regarding  this  serious  enemy  of  the  vine,  to  allay  the  alarm  of  those 
who  exaggerate  its  menace  to  the  industry,  and  at  the  same  time  to 
rouse  up  to  prompt  and  intelligent  action  those  who  are  inclined  to 
minimize  the  danger,  the  following  brief  account  is  issued. 

Historical. — The  phylloxera  is  a  native  of  the  United  States  east  of 
the  Rocky  Mountains,  where  it  is  found  living  upon  the  wild  vines.  It 
is  a  minute  insect  related  to  the  scale  insects  and  plant  lice.  It  was 
introduced  into  the  south  of  France  before  1863,  upon  rooted  vines  sent 
from  America;  though  the  insect  itself  was  not  found  and  described 
there  until  1868.  The  infection  commenced  at  two  points:  one  in  the 
southeast  in^Gard,  the  other  in  the  southwest  near  Bordeaux.  In  1868, 
when  the  nature  of  the  pest  was  understood,  it  had  already  invaded 
considerable  areas.  The  two  areas  first  attacked  gradually  enlarged 
until  they  touched  about  the  year  1880,  and  the  insect  began  to  spread 
northward.  By  1884  about  2,500,000  acres,  more  than  one  third  of  all 
the  vineyards  of  France,  had  been  destroyed  and  nearly  all  the  rest 
were  more  or  less  affected.  The  progress  of  the  disease  in  parts  of 
southern  France  was  so  rapid  that  in  some  towns  vine  stumps  became 
the  principal  fuel.  Since  1884  the  pest  has  continued  to  spread  with 
somewhat  less  rapidity  in  France,  partly  because  the  most  densely 
planted  vineyard  districts  had  already  been  devastated,  but  also  because 
elsewhere  its  progress  was  retarded  by  quarantine  and  other  restrictive 
measures.  No  remedies  yet  discovered,  however,  are  capable  of  exter- 
minating the  pest;  and  to-day  there  is,  no  vine-growing  region  of  any 
importance  in  France,  or  elsewhere,  exempt  from  phylloxera. 

The  insect  was  probably  introduced  into  California  upon  vines — cut- 
tings or  roots — imported  from  France,  though  it  was  possibly  introduced 
from  several  sources  and  at  several  points.     It  was  first  noticed  in  the 

62351 


southern  part  of  Sonoma  County  in  the  valley  surrounding  the  old  town 
of  Sonoma,  about  1874.  By  1880  vines  killed  by  the  insect  had  been 
found  in  Napa,  Solano,  and  Placer  counties,  and  hundreds  of  acres  had 
been  pulled  up  in  Sonoma  Valley.  Since  then  the  insect  has  spread  to  all 
the  important  grape-growing  regions  of  California  north  of  Tehachapi,* 
and  probably  not  less  than  30,000  acres  have  been  destroyed. 

The  Insect.—  The  phylloxera  occurs  normally  in  four  forms,  which 
have  been  called  by  Victor  Mayet: 

1.  The  gall  insect,  or  form  of  multiplication; 

2.  The  root  insect,  or  form  of  devastation ; 

3.  The  winged  insect,  or  form  of  colonization  ; 

4.  The  sexual  insect,  or  form  of  regeneration. 

The  gall  insect  lives  upon  the  leaves,  and  is  the  commonest  form  on 
the  wild  vines  in  the  native  habitat  of  the  insect.  It  rarely  occurs  in 
California.  In  Europe  it  is  found  often  upon  American  and  rarely  upon 
European  varieties.  It  causes  little  swellings  or  galls  upon  the  leaves 
and  younger  parts  of  the  vine,  which,  though  sometimes  very  numerous, 
do  little  permanent  injury.  The  chief  danger  from  the  gall  form  is  that 
it  multiplies  with  astonishing  rapidity  and  migrates  from  the  leaves  to 
the  soil.  Here  it  attacks  the  roots  and  gives  rise  to  the  root  form,  which 
is  the  "  form  of  devastation,"  the  one  which  finally  destroys  all  the  vines 
it  attacks  which  are  "non-resistant."  Every  insect  of  the  root  form 
which  reaches  maturity  lays  about  twenty-five  or  thirty  eggs,  each  of 
which  is  capable  of  developing  into  a  new  egg-layer  needing  no  fertiliza- 
tion. As  there  are  from  five  to  seven  such  generations  during  the  year, 
the  increase  in  numbers  is  extremely  rapid. 

Sometimes  during  the  summer,  usually  in  July  or  August,  some  of  the 
eggs  laid  by  the  root  insects  develop  into  insects  of  slightly  different 
form,  called  nymphs.  They  are  somewhat  larger  than  the  normal  root 
form' and  show  slight  protuberances  on  the  sides,  which  finally  develop 
into  wings.  These  are  the  winged  or  colonizing  insects,  which  emerge 
from  the  soil  and,  though  possessing  very  weak  powers  of  flight,  are 
capable  of  sailing  a  short  distance,  and  if  a  wind  is  blowing  may  be  taken 
many  rods  or  even  miles.  Those  which  reach  a  vine  crawl  to  the  under 
side  of  a  leaf  and  deposit  from  three  to  six  eggs.  These  eggs  are  of  two 
sizes,  the  smaller  of  which  produce  males  and  the  larger  females.  The 
female,  after  fertilization,  migrates  to  the  rough  bark  of  the  two-year- 
old  wood,  where  she  deposits  a  single  egg,  called  the  winter  egg,  which 
remains  upon  the  vine  until  the  following  spring.  The  insect  which 
hatches  from  this  egg  in  the  spring  goes  either  to  the  young  leaves  and 
becomes  a  gall-maker,  or  descends  to  the  roots  and  gives  rise  to  a  new 
generation  of  egg-laying  root-feeders.     The  normal  and  complete  life 

~^The  phylloxera  is  said  to  have  been  found  once  in  Southern  California;  but  as  the 
vineyard  was  uprooted  and  destroyed  the  insect  was  probably  extirpated. 


cycle  of  the  phylloxera  appears  then  to  be  as  follows :  Male  and  female 
insects  (1  generation  in  autumn);  gall  insects  (1-5  generations  while  the 
vines  are  in  leaf);  root  insects  (an  unknown  number  of  generations 
throughout  the  year);  nymphs,  which  become  winged  insects  (1  genera- 
tion in  midsummer).  The  gall  stage  may  be  omitted,  as  it  generally  is 
in  California,  and  the  insects  which  hatch  from  the  fertilized  eggs  laid 
by  the  female  go  directly  to  the  root  and  produce  offspring,  which  are 
indistinguishable  from  the  root  form  produced  in  the  normal  cycle. 
For  how  many  generations  the  root  form  can  exist  and  reproduce  with- 
out the  invigoration  supposed  to  come  from  the  production  of  the  sexual 
form  is  not  known,  but  certainly  for  four  years  and  probably  for  more. 
The  gall  form  on  American  vines  can  be  prevented  by  spraying  the  vines 
in  winter  with  liquids  to  kill  the  winter  eggs;  but  this  treatment  has  no 
effect  on  the  root  forms,  which  in  California  hibernate  abundantly  in 
the  soil. 

All  forms  of  the  phylloxera  are  extremely  minute,  the  root  form  being 
about  one  twenty-fifth  of  an  inch  long  when  it  reaches  the  adult  egg- 
laying  stage,  and  little  more  than  half  this  length  when  young  and 
active.  It  is  just  large  enough  to  be  seen  by  the  unaided  eye  in  a  good 
light  when  its  appearance  is  known,  and,  by  the  help  of  a  glass  magni- 
fying five  diameters,  its  legs  and  antennae  are  plainly  visible.  Its  color 
is  light  greenish-yellow  in  summer,  and  somewhat  darker  in  winter;  so 
that  when  numerous  the  attacked  roots  appear  as  though  dusted  in 
spots  with  powdered  mustard  or  cinnamon.  The  newly-hatched  insect 
is  fairly  active,  and  at  first  moves  about  from  place  to  place  on  the  roots; 
but  finally,  when  it  reaches  the  egg-laying  stage,  inserts  its  sucking-tube 
into  the  root  and  remains  fixed. 

Nature  of  Injury. — The  amount  of  nutriment  taken  from  the  vine  by 
such  minute  insects,  even  when  present  in  the  immense  numbers  in 
which  they  sometimes  occur,  is  not  sufficient  to  account  for  the  disas- 
trous effect  upon  the  plant.  The  death  of  the  vine  is  due  to  the  decay 
which  sets  in  wherever  the  phylloxera  has  attacked  the  roots.  Where- 
ever  a  phylloxera  inserts  its  sucking-tube  a  swelling  is  produced,  com- 
posed of  soft  tissue  which  soon  decays.  When  this  swelling  occurs  at 
the  end  of  a  young  rootlet,  growth  in  length  is  stopped;  when  it  occurs 
on  the  larger  roots,  a  kind  of  "cancer"  or  decay  spot  is  finally  formed, 
which  soon  extends  around  the  root,  and  all  below  the  point  of  attack 
dies. 

During  the  first  year  or  two  after  a  vine  is  attacked  there  is  little 
apparent  damage.  In  fact,  the  effect  of  the  phylloxera  is  equivalent  to 
root-pruning,  and  in  some  cases  results  in  an  unusually  large  crop  of 
grapes.  The  year  after  this  crop,  however,  the  vine  having  endured  the 
double  strain  of  heavy  bearing  and  root  injury  is  unable  to  recuperate, 


Fig.  1.    Young  roots  of  vine  attacked  by  Phylloxera. 

S— Nodosities  or  swellings  caused  by  the  insect. 

B— One  of  these  nodosities  enlarged,  showing  position  of  the  insects  (P) 
and  one-sided  character  of  the  swelling. 

Fig.  2.    Galls  or  swellings  caused  by  Nematode  worms,  which  occasionally  occur 
on  vine  roots  in  wet  soils.     Note  their  symmetrical  axial  character, 
which  distinguishes  them  from  Phylloxera  nodosities. 
M— Eggs  of  the  nematodes  found  in  these  galls. 


and  generally  dies. 

sudden,  and   two   or   even   three    small 

symptoms  of  the  disease  are  evident. 


In  rich,  moist  soil  the  death  of  the  vine  is  not  so 


crops  may  be  obtained   after 


Methods  of  Dispersal. — The  ways  in  which  new  vines  and  vineyards 
become  infested  may  be  classed  as  natural  and  artificial.  The  natural 
ways  may  be  inferred  from  what  has  been  said  of  the  life  history  of  the 
insect.  From  a  vine  first  attacked  the  root  form  spreads  through  the 
soil  to  neighboring  vines  slowly,  but  continuously,  thus  forming  the  so- 
called  "  oil-spots. "  A  typical  oil-spot  of  several  years'  standing  will 
show  several  dead  vines  in  the  center,  then  a  ring  of  vines  with  very 
short  growth  and  no  grapes,  next  another  ring  where  the  growth  is  not 
of  normal  vigor,  but  where  the  crop  may  be  equal  to  or  larger  than  that 
of  the  healthy  vines.  Such  a  spot  enlarges  its  area  year  after  year  at  a 
gradually  accelerating  rate  as  the  front  of  the  invading  army  becomes 
longer.  The  rate  of  advance  will  vary  with  the  soil  and  climate,  but 
will  probably  never  exceed  forty  or  fifty  feet  annually.  If  this  were 
its  only  method  of  spreading,  the  insect  could  be  controlled  or  even 
exterminated  with  comparative  ease.  Unfortunately,  it  is  able  to 
spread  much  more  rapidly  by  means  of  the  winged  form;  and  the 
rapidity  of  its  extension  over  the  south  of  France  was  due  principally 
to  this  agency.     In  California,  though  the  winged  form  has  been  found, 


—  7  — 

it  seems  to  be  rare,  which  probably  accounts  to  some  extent  for  the 
comparative  slowness  with  which  new  districts  have  become  infested. 
The  artificial  methods  of  dispersal  are  here  probably  more  effectual  in 
spreading  the  insect  than  the  natural.  The  insects  are  taken  from  one 
part  of  the  vineyard  to  another  on  pieces  of  the  roots  of  infested  vines, 
adhering  to  the  plows  or  other  implements  used  in  cultivation;  while 
they  are  introduced  into  new  localities  on  rooted  vines  or  cuttings 
brought  from  infested  districts. 

METHODS    OF    COMBATING   THE    PEST. 

The  methods  to  be  used  in  resisting  this  foe  of  the  vineyardist  may  be 
divided  into  groups  corresponding  to  different  stages  of  infection  and 
to  varying  local  conditions.  There  are  three  cases  to  be  distinguished, 
viz: 

1.  The  district  is  uninfested; 

2.  A  few  small  infested  spots  are  known  in  the  district; 

3.  The  district  is  badly  infested;  i.  e.,  shows  many  and  widely  dis- 
tributed infested  spots,  even  though  none  of  the  spots  is  large. 

1.  In  the  first  case,  all  efforts  should  be* directed  to  keeping  out  the 
pest,  and  the  only  effectual  means  is  a  rigidly  enforced  embargo  on  all 
material  capable  of  introducing  it.  Wherever  the  vineyard  interest  is 
of  sufficient  importance  this  should  extend  to  the  exclusion  from  infested 
districts,  not  only  of  all  vine  roots  and  cuttings,  but  also  of  all  other 
plants,  such  as  nursery  stock,  potatoes,  etc.,  which  are  taken  from  below 
the  ground.  Although  the  phylloxera,  so  far  as  known,  feeds  on  nothing 
but  the  vine,  there  is  always  danger  of  eggs  or  insects  being  contained 
in  the  earth  attached  to  any  kind  of  root.  This  measure,  consistently 
carried  out,  has  kept  the  province  of  Algiers  free  from  infection,  though 
the  neighboring  province  of  Constantine  has  been  a  prey  to  the  pest  for 
many  years. 

2.  In  the  second  case,  where  the  insect  has  already  obtained  a  foot- 
hold, the  first  step  to  take  is  to  determine  as  nearly  as  possible  the 
exact  extent  of  the  infested  area.  If  it  is  found  to  be  confined  to  a 
small,  isolated  vineyard,  an  effort  should  be  made  to  completely  eradi- 
cate the  pest.  This  can  be  done  only  by  destroying  the  vineyard,  by 
subjecting  it  to  what  is  called  the  "death  treatment."  This  is  best  done 
(after  grubbing  up  the  vines  and  burning  them  on  the  ground)  by 
making  an  embankment  around  the  whole  vineyard  and  then  running 
water  on  to  it  until  it  is  converted  into  a  lake.  The  water  should  be 
kept  continuously  at  a  depth  of  at  least  six  inches  until  all  the  insects 
are  destroyed.  The  best  time  to  do  this  is  in  May  or  June,  as  at  that 
time  four  weeks'  continuous  flooding  is  sufficient  to  kill  both  insects  and 
roots.  It  is  important  that  every  root  should  be  killed  in  order  that,  if 
any  insect  survives  the  flooding,  it  will  die  for  lack  of  food.     Where 


—  8  — 

flooding  is  impracticable,  the  vines  should  be  grubbed  out  and  burned 
in  the  same  way,  and  the  ground  kept  clean  of  all  growth  for  at  least 
one  year.  This  is  in  order  that  any  suckers  which  may  come  up  from 
the  roots  may  be  destroyed  immediately.  If  crops,  or  even  weeds,  are 
allowed  to  grow,  some  of  these  suckers  may  escape  observation  and 
serve  to  keep  the  insects  alive  to  spread  the  pest  the  next  year.  If  the 
affected  spot  is  not  too  large  it  is  well  to  disinfect  the  soil  with  bisulfid 
of  carbon.  This  is  applied  by  pouring  one  ounce  each  into  holes  placed 
two  feet  apart  all  over  the  land  to  be  treated.  These  holes  should  be 
about  one  foot  deep  and  can  be  made  with  a  small  crowbar  or  dibble. 
After  pouring  in  the  liquid,  the  hole  should  be  closed  by  pressing  earth 
into  it  with  the  foot. 

If,  however,  the  pest  has  obtained  a  foothold  in  several  vineyards  of 
the  district,  or  in  a  large  vineyard,  it  is  practically  hopeless  to  attempt 
to  eradicate  it.  In  this  case  all  we  can  reasonably  hope  to  do  is  to 
delay  the  spread  of  the  pest  as  much  as  possible  and  in  the  meantime 
to  place  all  new  vineyards  on  a  permanently  phylloxera-resistant  basis. 
Every  infested  spot  in  the  district  should  be  diligently  sought  out  and 
treated.  The  treatment  consists  in  digging  up  and  burning  every  vine 
in  each  spot  which  shows  symptoms  of  attack,  together  with  at  least 
three  rows  of  apparently  healthy  vines  surrounding  them.  Disinfection 
of  the  soil  of  these  spots  by  flooding  or  with  bisulfid  of  carbon  is  then 
advisable  wherever  practicable,  but  in  any  case  these  spots  should  be 
strictly  isolated  in  all  farming  operations.  In  cultivating  the  healthy 
parts  of  the  vineyard,  to  pass  through  the  infested  spots  with  plows  or 
hoes  is  a  most  effective  method  of  accelerating  the  spread  of  the  insect. 
The  search  for  infested  spots  is  most  easily  and  thoroughly  done  in  July 
or  August,  as  at  that  time  the  shortness  of  growth  in  the  "  oil-spots"  is 
most  readily  detected  and  the  insects  are  easily  found,  as  they  are  in 
large  numbers  on  the  surface  roots  and  generally  also  on  the  trunk  of 
the  vine  just  below  the  surface  of  the  soil.  The  search  for  and  destruc- 
tion of  infested  spots  should  be  repeated  every  year;  and  if  commenced 
in  the  early  stages  of  infection  and  prosecuted  with  sufficient  thorough- 
ness in  every  vineyard  throughout  a  district,  will  effectually  prolong  the 
life  of  the  bulk  of  the  vines  for  many  years.  As  soon  as  the  actual 
presence  of  the  phylloxera  in  a  district  is  known  and  all  hopes  of  per- 
manently eradicating  it  are  abandoned,  the  embargo  should  be  modified 
to  the  extent  of  admitting  vine  cuttings.  These  should  be  introduced, 
however,  under  strict  quarantine  regulations,  including  disinfection  by 
responsible  and  properly  instructed  persons.  Rooted  vines,  or  cuttings 
with  pieces  of  old  wood  attached,  should  still  be  kept  out,  as  they 
cannot  be  disinfected  with  any  certainty. 

3.  However  conscientiously  and  completely  these  measures  are 
enforced,  a  time  will  arrive  sooner  or  later  when  the  cost  of  inspection 


—  9  — 

and  eradication  will  be  greater  than  any  benefit  to  be  derived  from 
them.  We  are  then  face  to  face  with  the  third  set  of  conditions;  we 
must  accept  the  phylloxera  as  a  permanent  inhabitant  of  the  district 
and  simply  consider  the  best  method  of  growing  our  vines  in  spite  of  its 
presence.  By  this  time  all  embargo  or  quarantine  regulations  are  use- 
less and  should  be  repealed. 

Of  the  many  thoue&nds  of  methods  proposed  and  tested  for  maintain- 
ing a  vineyard  in  spite  of  the  phylloxera  but  very  few  have  been  of  the 
slightest  practical  value  and  only  four  are  at  present  used  to  any 
important  extent.     These  methods  are: 

1.  Injection  of  carbon  bisulfid; 

2.  Flooding  or  submersion; 

3.  Planting  in  sand; 

4.  Planting  resistant  vines. 

The  first  two  methods  aim  at  destroying  the  insect ;  the  last  two,  at 
rendering  the  vines  immune  to  their  attack.  As  neither  of  the  insecti- 
cidal  methods  can  be  applied  with  sufficient  thoroughness  to  completely 
eradicate  the  pest  without  also  killing  the  vines,  the  treatments  have  to 
be  repeated  every  year  in  order  to  destroy  the  offspring  of  the  few 
insects  which  escape  the  treatment  of  the  previous  year.  For  this 
reason  these  methods  are  being  abandoned  everywhere,  especially  in  all 
new  plantings,  in  favor  of  the  others,  which  after  the  vineyard  is 
properly  started  involve  no  further  expense ;  and  as  planting  in  sand 
is  of  very  limited  and  local  applicability,  it  may  be  said  that  at  present 
the  only  method  that  need  concern  grape-growers  in  California  very 
seriously  is  the  use  of  resistant  vines.  This  tendency  to  resort  to 
resistant  vines  to  the  exclusion  of  all  other  methods  is  well  illustrated 
by  the  following  statistics  of  the  vineyards  of  Herault,  one  of  the  chief 
grape-growing  districts  of  France,  and  that  in  which  the  conditions 
most  resemble  those  of  California : 


Acres  of  Vines. 

1880. 

1890. 

1899. 

1.  Treated  with  carbon  bisulfid  _ 

6,600 
3,900 

6,200 

15,000 

9,900 

311,000 

800 

2.  Submerged 

11,000 

1,200 

440,000 

3.  Planted  in  sand _ 

4.  Resistant  vines 

6,600 

Bisulfid  of  carbon  is  a  liquid  which  volatilizes  very  rapidly  at  ordi- 
nary temperatures  and  gives  off  a  poisonous  and  highly  inflammable 
vapor.  This  vapor  is  heavier  than  air  and  therefore  gradually  replaces 
and  saturates  the  air  in  the  interstices  of  the  soil  when  the  liquid  is 


—  10  — 

injected.  It  is  used  at  the  rate  of  from  125  to  250  pounds  per  acre,  and 
may  be  applied  at  any  time  except  during  blossoming  and  the  ripening 
of  the  fruit.  Two  treatments,  one  directly  after  the  vintage  and  the 
other  a  week  or  so  before  blossoming,  give  the  best  results.  The  liquid 
is  applied  by  pouring  from  \  to  f  ounce  into  holes  made  from  18  inches 
to  2  feet  apart  all  over  the  vineyard,  care  being  taken  not  to  put  any 
nearer  than  1  foot  from  a  vine.  The  holes  are  made  from  12  to  15 
inches  deep,  and  are  closed  immediately  after  pouring  in  the  liquid  by 
pressing  the  soil  with  the  foot.  The  holes  may  be  made  with  an  iron 
rod  or  dibble  ;  but  where  the  method  is  employed  on  a  large  scale 
special  injectors  are  used,  which  much  facilitate  the  work.  The  injec- 
tions are  best  made  when  the  soil  is  fairly  firm,  and  when  it  is  neither 
very  wet  nor  very  dry.  This  method  succeeds  only  in  rich,  deep,  loose 
soils,  and  cannot  be  used  successfully  in  soil  containing  much  clay,  or 
on  dry,  rocky  hillsides.  It  is  most  effective  in  sandy  soils,  where  the 
nature  of  the  soil  is  itself  unfavorable  to  the  insect.  It  is  least  success- 
ful in  warmer  locations,  where  the  insect  is  most  prolific  and  most 
harmful,  and  is  used  chiefly  in  the  cooler  locations  where  the  phylloxera 
does  least  damage.  Vines  which  are  much  weakened  by  the  attacks  of 
the  insects  cannot  be  successfully  treated,  and  all  treated  vines  require 
fertilization  and  most  thorough  cultivation.  The  annual  cost  for  mate- 
rial alone  would  be  from  $15  to  $25  per  acre,  at  the  present  market  price 
of  carbon  bisulfid. 

Submersion  is  a  cheaper  and  more  effective  method  of  controlling 
phylloxera,  but  is  necessarily  applicable  to  but  few  locations,  and  even 
where  most  successful  is  gradually  giving  way  to  the  more  satisfactory 
use  of  resistant  vines.  Its  chief  use  is  to  preserve  vineyards  which  are 
already  in  bearing,  and  it  may  be  of  use  temporarily  in  some  locations 
in  California.  During  submersion  the  vineyard  must  be  covered  con- 
tinuously with  at  least  six  inches  of  water,  as  the  object  is  to  drown  the 
insects;  that  is,  to  kill  them  by  depriving  them  of  air.  If  the  surface 
becomes  exposed  even  for  a  brief  interval  air  will  be  absorbed  and  the 
insects  given  a  new  lease  of  life.  In  very  porous  soils  submersion  is 
impracticable  on  account  of  the  large  amount  of  water  required,  and 
ineffective  for  the  reason  that  the  rapid  passage  of  the  water  carries  suf- 
ficient air  into  the  soil  to  keep  the  insects  alive.  Submersion  is  most 
effective  in  destroying  the  insects  when  they  are  in  their  most  active 
condition,  that  is,  in  summer.  At  this  time,  unfortunately,  the  vine  is 
also  most  sensitive  to  injury.  The  most  favorable  time,  then,  for  sub- 
mersion is  as  soon  as  the  vines  have  ceased  active  growth  and  before 
the  phylloxera  have  entered  their  hibernating  or  dormant  condition. 
This  in  most  parts  of  California  will  be  some  time  in  October.  At  this 
period  the  flooding  need  last  but  a  week  or  ten  days;  a  month  later,  two 
or  three  weeks;  while  during  the  remainder  of  the  winter  little  good 


—  11  — 

results  unless  the  submersion  is  prolonged  for  thirty-five  or  forty  days, 
and  indeed  in  some  soils  of  the  extreme  south  of  France  two  months  has 
been  found  necessary.  As  the  insect  is  most  susceptible  in  midsummer, 
it  was  at  one  time  thought  that  a  copious  irrigation  at  that  time  suffi- 
cient to  destroy  most  of  the  insects  without  injuring  the  vines  could  be 
effected.  At  present  a  flooding  in  July  for  not  exceeding  forty-eight 
hours  is  practiced  in  a  few  places,  but  only  to  supplement  winter-flood- 
ing, or  the  injection  of  bisulfid.  The  insecticidal  value  of  the  short 
submersion  which  the  vines  will  withstand  at  this  time  seems  to  be  very 
slight.  Its  main  value  seems  to  be  in  promoting  a  vigorous  growth  of 
new  rootlets  to  replace  those  that  have  been  injured. 

Planting  in  Sand. — Though  no  thoroughly  satisfactory  explanation 
has  been  given,  the  fact  is  established  that  in  certain  very  sandy  soils 
vines  are  uninjured  by  phylloxera.  All  sandy  soils  are  unfavorable  to 
the  increase  of  the  insect,  and  vines  planted  in  them  die  more  slowly 
than  in  others;  but  for  complete  immunity  the  soil  must  contain  at  least 
60  per  cent  of  siliceous  sand.  The  looser  and  more  fine-grained  the  sand, 
the  more  resistance  it  offers  to  the  insect.  Calcareous  sands,  those 
containing  notable  quantities  of  clay,  all  those  in  fact  which  have  a 
tendency  to  form  in  lumps  or  "cake,"  offer  less  resistance. 

EESISTANT    VINES. 

The  most  satisfactory  method  of  combating  phylloxera  is  the  use  of 
resistant  vines,  because  it  is  applicable  to  all  conditions  and  is  the  most 
economical  in  the  end.  A  resistant  vine  is  one  which  is  capable  of  keep- 
ing alive  and  growing  even  when  phylloxera  are  living  upon  its  roots. 
Its  resistance  depends  on  two  facts:  first,  that  the  insects  do  not  increase 
so  rapidly  on  its  roots;  and  second,  that  the  swellings  of  diseased  tissue 
caused  by  the  punctures  of  the  insects  do  not  extend  deeper  than  the 
bark  of  the  rootlets  and  are  sloughed  off  every  year,  leaving  the  roots 
as  healthy  as  before.  The  wild  vines  of  the  Mississippi  States  have 
evolved  in  company  with  the  phylloxera,  and  it  is  naturally  among 
these  that  we  find  the  most  resistant  forms.  No  vine  is  thoroughly 
resistant  in  the  sense  that  phylloxera  will  not  attack  it  at  all;  but  on 
the  most  resistant  the  damage  is  so  slight  as  to  be  imperceptible.  The 
European  vine  (Vitis  vinifera,  L.)*  is  the  most  susceptible  of  all,  and 
all  the  grapes  cultivated  in  California,  with  a  few  unimportant  excep- 
tions, belong  to  this  species.  Between  these  two  extremes  we  find  all 
degrees  of  resistance,  which  is  expressed  by  a  series  of  numbers  ranging 
from  20,  indicating  the  highest  possible  resistance,  to  0,  indicating  the 
utmost  susceptibility.  The  following  table  shows  the  resistance  (accord- 
*See  frontispiece. 


12  — 


ing  to  Viala  and  Ravaz  and  other  authorities)  of  some  of  the  best  known 
species  and  varieties: 

Comparative  Resistance  to  Phylloxera. 


Species  (Wild  Vines). 


Cultivated  Varieties  and  Hybrids. 


Vitis  rotundifolia 19 

Vitis  vulpina  (riparia) 18 

Vitis  rupestris . 18 

Vitis  Berlandieri _ 17 

Vitis  aestivalis 16 

Vitis  labrusca 5 

Vitis  Californica 4 

Vitis  vinifera 0 


Gloire  de  Montpellier  (Riparia) 18 

Riparia  X  Rupestris  3309 18 

Rupestris  Martin 18 

Rupestris  St.  George  .. 16 

Riparia  X  Solonisl616 16 

Solonis _._ 14 

Lenoir 12 

Isabella... 5 


The  degree  of  resistance  necessary  for  the  production  of  good  crops 
varies  with  the  character  of  the  soil.  The  resistance  expressed  by  the 
numbers  16  to  20  is  sufficient  for  all  soils.  A  resistance  of  14  or  15  is 
sufficient  in  sandy  and  moist,  rich  soils,  where  the  vine  can  readily 
replace  the  rootlets  as  fast  as  they  are  destroyed.  Fairly  successful 
vineyards  have  been  established  exceptionally  with  vines  having  a 
resistance  of  less  than  14,  but  as  the  vines  become  old  the  lack  of 
resistance  is  generally  shown  by  a  weakening  of  the  vine  and  a  falling 
off  of  the  crop.  Many  vineyards  in  the  south  of  France  grafted  on 
Lenoir  which  formerly  bore  well,  have  now  to  be  doctored  with  injec- 
tions of  bisulfid.  For  this  reason  it  is  advisable  to  reject  all  vines 
with  a  resistance  of  13  or  under,  especially  as  vines  with  greater 
resistance  can  now  be  obtained  for  practically  all  conditions. 

Resistant  vines  are  of  two  kinds:  (a)  those  which  are  grown  for  the 
grapes  they  produce,  and  (b)  those  which  are  useful  only  as  stocks  on 
which  to  graft  the  non-resistant  varieties.  The  former  are  called 
u  direct  producers  "  the  latter,  "  resistant  stocks." 

(a)  Direct  Producers. — When  the  phylloxera  commenced  to  destroy 
the  vineyards  of  Europe,  the  natural  attempt  was  made  to  replace  them 
with  the  varieties  of  vines  which  had  proved  successful  in  the  United 
States,  where  the  insect  was  endemic.  These  varieties,  however,  all 
proved  unsatisfactory.  Some,  like  the  Concord  and  the  Catawba,  were 
insufficiently  resistant,  and  although  they  could  be  grown  where  the 
severe  cold  of  winter  impeded  the  prolificness  of  the  phylloxera,  they 
quickly  succumbed  in  the  milder  grape-growing  sections  of  Europe.* 
Most  of  them  were  poor  bearers  compared  with  the  prolific  European 
vines,  and  finally  the  character  of  their  fruit  differed  so  widely  from 
what  Europeans  were  accustomed  to  that  there  was  little  sale  for  the 
fruit,  and  the  wine  could  compete  with  only  the  very  poorest  quality  of 

*  In  California,  these  and  other  Labrusca  varieties  and  hybrids  resist  very  little  longer 
than  Vinifera  vines. 


—  13  — 

Vinifera  wines,  and  brought  a  very  inferior  price.  A  few  of  the  varieties 
introduced  during  that  first  period  are  still  grown  to  a  limited  extent  in 
France,  chiefly  the  Othello  and  the  Lenoir.  They  are  being  gradually 
abandoned,  however,  as  their  crops  are  unsatisfactory,  and  in  many 
localities  can  be  maintained  only  by  the  aid  of  injections  of  bisulfid. 
For  some  years  the  search  for  a  suitable  direct  producer  was  almost 
abandoned  by  practical  men,  the  use  of  resistant  stocks  having  been  so 
fully  successful.  Lately,  however,  renewed  efforts  have  been  made  and 
several  new  direct  producers  are  being  advocated  and  planted  to  some 
extent.  The  merit  of  these  new  varieties,  however,  is  chiefly  their 
resistance  to  Peronospora  and  Black  Rot.  Phylloxera-resistance  is  con- 
sidered of  much  less  importance  by  their  most  ardent  advocates,  and 
indeed  the  advice  is  given  to  graft  some  of  the  best  of  these  direct  pro- 
ducers upon  phylloxera-resistant  stock.  The  main  importance  of  these 
facts  to  California  grape-growers  is  that  they  hold  out  hopes  of  perma- 
nent prosperity  for  the  wine-making  industry  here,  where,  owing  to  the 
dryness  of  the  climate,  there  is  no  likelihood  of  trouble  from  these 
serious  fungous  diseases  of  the  grape,  which  threaten  to  make  the  grow- 
ing of  Vinifera  varieties  impossible  in  many  parts  of  Europe. 

(b)  Resistant  Stocks. — Though  high  resistance  to  phylloxera  is  essential 
in  a  grafting  stock,  there  are  other  characteristics  equally  necessary. 
The  Rotundifolia  ( Scupper nong)  which  has  the  highest  resistance  of  any 
vine,  is  useless  as  a  stock  on  account  of  the  impossibility  of  grafting  it  with 
any  Vinifera  variety.  This  is  due  to  a  lack  of  affinity,  which  means  a 
lack  of  similarity  in  structure  and  composition  between  the  tissues  of  the 
stock  and  those  of  the  scion.  This  lack,  in  extreme  cases,  results  in  an 
imperfect  and  temporary  union,  but  when  not  excessive,  only  in  a  slight 
decrease  of  vigor.  The  affinity  is  not  perfect  between  Vinifera  varieties 
and  any  resistant  stock,  but  in  the  case  of  Riparia  and  Rupestris  is 
generally  sufficient  to  insure  permanence  to  the  union,  and  the  slight 
decrease  of  vigor  consequent  often  results  in  an  increase  of  fruitfulness. 
It  is  for  this  reason  that  certain  varieties  when  grafted  on  resistant  stocks, 
especially  on  Riparia,  often  bear  larger  crops  than  when  grown  on  their 
own  roots.  Not  all  varieties  of  Vinifera  have  the  same  affinity  for  the 
same  stock.  For  this  reason  it  is  desirable  to  be  cautious  about  making 
new  or  untried  grafting  combinations  on  a  large  scale.  Some  varieties, 
such  as  Carignan,  Petite  Sirah,  Clairette,  and  Cabernet  Sauvignon  do 
excellently  on  all  stocks;  while  others,  such  as  Mondeuse  and  Gamay 
do  not  make  a  very  good  union  with  any  of  the  thoroughly  resistant 
stocks.  The  Petit  Bouschet  and  Cinsaut  make  very  poor  unions  with 
any  variety  of  Riparia,  but  do  fairly  well  on  Rupestris  St.  George.  The 
Pinot  Noir  makes  a  vigorous  growth  upon  Rupestris  St.  George  but 
bears  much  more  prolifically  upon  Riparia  Gloire;   while  the  Mataro 


—  14  — 

does  not  bear  on  Rupestris  St.  George  and  makes  poor  unions  with 
Riparia  Gloire.* 

Selection. — A  very  serious  defect  of  many  resistant  stocks  is  a  slender 
habit  of  growth.  This  is  true  of  most  of  the  vines  found  growing  wild, 
and  cuttings  from  such  vines  make  poor  grafting  stock  for  the  stout 
Vinifera  varieties,  which  will  produce  a  trunk  four  inches  in  diameter 
while  the  stock  is  growing  only  two  inches.  This  is  particularly  true  of 
the  wild  Riparias.  For  this  reason  great  care  has  been  exercised  in 
selecting  the  stronger-growing  forms,  and  at  present  we  have  selected 
Riparia-varieties  which  almost  equal  Vinifera  in  the  stoutness  of  their 
trunks.  The  best  of  these  are  the  Riparia  Gloire  de  Montpellier  and 
the  Riparia  Grande  Glabre,  the  first  of  which  has  given  the  best  results 
in  California. 

Adaptation. — The  European  vine  is  remarkable  among  cultivated 
plants  for  the  wide  range  of  soils  in  which  it  will  succeed.  We  find 
vineyards  producing  satisfactory  crops  on  the  lightest  sands  and  on  the 
heaviest  clays,  on  the  dry  hill-tops  and  in  the  low,  moist  plains.  This 
is  not  the  case  with  resistant  stocks.  Some,  such  as  the  Rupestris 
varieties,  are  suited  to  the  driest  soils;  others,  like  the  Riparia  varieties, 
grow  well  only  on  rich,  moist  soils.  The  question  of  the  adaptation, 
then,  of  resistant  stocks  to  various  soils  is  of  the  greatest  importance  if 
we  are  to  obtain  the  best  results. 

After  rejecting  all  unselected  and  unnamed  varieties,  such  as  the 
ordinary  Rupestris  and  Riparia,  which  have  caused  so  much  disappoint- 
ment and  loss  on  account  of  their  poor  growth,  and  all  insufficiently 
resistant  varieties,  such  as  Lenoir,  which  have  succeeded  only  in  the 
richest  soils,  our  choice  of  a  resistant  for  a  particular  soil,  climate,  and 
scion  must  depend  on  its  qualifications  as  regards  affinity  and  adaptation. 

After  testing  hundreds,  if  not  thousands,  of  varieties  and  hybrids 
originated  in  Europe  and  America,  a  few  have  been  selected  as  the  best 
for  practical  purposes.  In  France  a  fairly  good  resistant  stock  has  been 
found  for  nearly  every  soil.  In  California  little  systematic  work  has 
been  done  in  this  respect,  and  we  still  have  the  intricate  problems 
of  adaptation  to  solve  for  most  localities.  We  can,  however,  profit  to 
some  extent  by  the  experience  of  Europe,  and  some  of  the  best  varieties  . 
have  been  partially  tested  here  and  give  great  promise. 

For  the  driest  soils,  on  hillsides  with  a  southern  exposure,  the 
Rupestris  Martin  is  the  most  promising  variety.  Though  not  quite 
such  a  vigorous  grower  as  the  St.  George  it  has  greater  resistance  to 
phylloxera,  and  where  grafted  has  given  equal  if  not  superior  results. 
Where  the  soil  is  somewhat  compact  the  Rupestris  St.  George  is  to  be 
preferred,  but  neither  of  them  should  be  planted  where,  on  account  of 
*"Reconstitution  du  Vignoble,"  par  P.  Gervais,  1900. 


__  15  — 

an  impervious  subsoil  or  a  high  water-table,  deep  penetration  of  the 
roots  is  impossible. 

For  very  shallow  soils  no  resistant  has  been  found  that  gives  perfectly 
satisfactory  results,  but  in  such  situations  Riparia  often  does  better 
than  Rupestris.  Where  ground  water  is  too  near  the  surface  Rupestris 
is  liable  to  fungous  root-rot.  Near  Mission  San  Jose  there  are  vine- 
yards on  rolling  hills  where  the  soil  consists  of  a  layer,  from  2  to  4  feet 
thick,  of  the  heaviest  black  adobe  underlaid  by  a  sandy  subsoil.  Here 
Riparia  has  grown  more  vigorously  and  produced  better  crops  than 
Rupestris.  The  subsoil,  though  easily  penetrated  by  vine  roots  and 
favorable  to  their  growth  in  normal  seasons,  loses  its  water,  which  is 
taken  up  by  the  more  hygroscopic  surface  clay  in  dry  years.  In  such 
conditions  the  deep-rooted  Rupestris  suffers,  while  the  Riparias,  with 
all  their  roots  in  the  adobe,  remain  vigorous. 

For  loose,  moist  soils  on  northern  slopes,  and  in  those  situations 
where  a  horizontal  root  development  is  desirable  or  permissible,  the 
Riparia  Gloire  de  Montpellier  is  extremely  promising.  It  should  be 
planted  wherever  Riparias  of  any  kind  have  proved  to  do  well,  as  in 
certain  soils  and  locations  in  the  San  Francisco  Bay  region,  and  in  the 
sub-irrigated  soils  of  parts  of  the  San  Joaquin  Valley.  Other  very 
promising  resistants  are  certain  hybrids  of  Rupestris  and  Riparia, 
which  in  many  ways  combine  the  merits  of  both  species.  Of  these, 
Riparia  X  Rupestris  3309  and  Riparia  X  Rupestris  10114  have  given 
the  most  favorable  impression  in  California.  They  are  strong,  vigorous 
growers,  with  a  greater  range  of  adaptation  than  the  pure  species,  and 
a  resistance  to  phylloxera  equal  to  that  of  Riparia  Gloire. 

DISINFECTION   OF    CUTTINGS. 

The  simplest  and  most  effective  method  of  treating  cuttings  suspected 
of  being  infected  with  phylloxera  is  to  expose  them  to  the  fumes  of 
bisulfld  of  carbon.  The  treatment  with  liquid  insecticides  is  not  nearly 
so  reliable,  as  Professor  Hilgard  pointed  out  many  years  ago,  on  account 
of  the  difficulty  of  wetting  the  buds  of  many  varieties,  owing  to  their 
protective  covering  of  woolly  hairs.  Some  fear  has  been  expressed  that 
the  poisonous  fumes  would  injure  the  vitality  of  cuttings,  but  Professor 
Hilgard  demonstrated  in  1881  that  Zinfandel  cuttings  kept  for  twelve 
hours  in  an  atmosphere  saturated  with  the  fumes  showed  no  signs  of 
injury,  and  grew  as  well  as  untreated  cuttings.  Recent  tests  with  resist- 
ant cuttings,  Riparia  and  Rupestris,  indicate  that  they  can  be  treated 
with  equal  safety,  for  even  after  twenty-five  hours'  treatment  they  were 
not  killed,  though  their  slowness  in  starting  and  callusing  indicated 
that  they  were  injured.  After  five  hours'  treatment  Rupestris  St.  George 
cuttings  were  uninjured  and  sent  out  roots  and  buds  vigorously  and 
rapidly.     A  large  lot  (about  4,000  cuttings)  of  Rupestris  St.  George, 


—  16  — 

Rupestris  X  Riparia  3309,  Riparia  Gloire,  and  Solonis  were  exposed  in 
a  saturated  atmosphere  of  carbon  bisulfid  for  seven  hours,  and  at  the 
present  time  they  are  rooting  and  show  no  signs  of  injury.  As  Professor 
Hilgard's  experiments  in  1881  showed  that  one  half  hour  exposure  was 
sufficient  to  destroy  the  summer  eggs  of  the  insect,  the  time  latitude  is 
quite  sufficient  for  safety,  even  for  the  winter  egg. 

The  method  of  using  the  bisulfid  is  as  follows:  Place  the  cuttings  in 
a  barrel,  vat,  or  box  made  tight  by  means  of  a  thick  coat  of  paint,  or  of 
paper  pasted  on  the  inside.  On  top  of  the  cuttings  place  a  saucer  or 
other  shallow  dish,  into  which  to  pour  the  bisulfid  of  carbon.  An 
ordinary  saucer  will  hold  enough  for  a  box  3  feet  cube  or  a  200-gallon 
vat.  For  larger  receptacles  it  is  better  to  use  two  or  more  saucers. 
Deeper  vessels  will  not  do,  as  the  saturation  is  not  sufficiently  rapid. 
After  pouring  the  bisulfid  into  the  saucer,  cover  the  box  with  an  oiled 
canvas  sheet  or  other  tight-fitting  cover,  and  allow  to  stand  for  from 
forty-five  to  ninety  minutes.  At  the  end  of  this  time  there  should  be  a 
little  of  the  bisulfid  left.  If  it  has  all  evaporated  this  is  proof  that  insuffi- 
cient was  used.  No  flame  lights  should  be  used,  as  the  liquid  burns  easily 
and  the  fumes  form  an  explosive  mixture  with  the  air.  Care  should  be 
taken  not  to  spill  any  of  the  liquid  on  the  cuttings,  as  it  may  kill  them. 
It  is  advisable  to  cut  off  about  half  an  inch  of  the  lower  end  of  the 
treated  cuttings  before  planting,  as  the  vapor  injures  the  open  pith. 

Besides  disinfecting  the  cuttings  in  this  way,  all  the  packing  material 
in  which  they  come  should  be  burnt,  or  if  valuable,  dipped  in  boiling 
water.  Practically  it  is  impossible  to  disinfect  rooted  cuttings  satis- 
factorily on  account  of  the  difficulty  of  killing  all  the  phylloxera 
without  seriously  injuring  the  vine  roots. 


